Telephone ringer



Patented July 30, 1940 UNITED STATES PATENT OFFICE.

TELEPHONE RINGER Application March 10,

4 Claims.

This invention relates to electromagnetically operated devices andparticularly to electromagnetically operated signaling devices of thetype commonly known as telephone ringers.

The telephone ringer in general use today comprises essentially, anelectromagnet which when energized causes the operation of an armatureto which there is staked, or otherwise secured, a striker-rod whose freeend extends between two 10 gongs in such a manner as to strike the gongsalternately when the electromagnet is energized.

The armatures of such devices have been supported heretofore on astationary yoke piece either by means of shafts, metallic pivots orthrough the medium of a reed-type hinge. Such methods of support, thoughsatisfactory in the past, do not meet present-day requirements. Incurrent telephone designs such supports are not sufliciently rugged towithstand long periods of service without adjustments, are aiTected bythe environment of dirt and dust, require lubrication and, in shaft andpivot constructions, present an impedance to desired armature motionwhich varies with time due to wear.

Also, in current telephonedesigns. one class of service requires a loudsignal while another class requires a weak signal of pleasing tonequality and it is desirable that a single ringer design satisfy bothclasses.

An object of this invention is to provide an improved type of mountingfor the armatures of electromagnetically operated devices and one whichovercomes the inherent weaknesses of the shaft, pivot and reed types.

Another object of the invention is to render the sound output of atelephone ringer 'more pleasant in character by reducing the mechanicalnoise and to provide means whereby the volume of sound produced can beregulated to suit the user.

The improved armature support is obtained in accordance with a featureof the invention by the provision of a torsional mounting which isrugged, requires no lubrication, is unaifected by the environment ofdirt or dust and which presents an impedance to desired armature mo tionwhich is substantially constant over a long period of time. Morespecifically, the armature is supported on its associated stationaryyoke piece by means of an elastic material, such as rubber.

In accordance with another feature of the invention, the sound qualityof the telephone ringer is improved by acoustically and mechanicallyinsulating the gongs from their supports and by 1931, Serial No. 130,035

cushioning the end of the armature stroke by means of resilient armaturestops instead of the rigid metal stops heretofore employed. The soundpower produced by the ringer may be adjusted by substituting stops ofdifferent thicknesses thereby changing the length of the armaturestroke.

The invention will be readily understood from the following detaileddescription made with reference to the accompanying drawing in which:

Fig. 1 is a side elevation of a telephone ringer embodying the featuresof this invention;

Fig. 2 is a section taken along the line 1 -2 oi Fig. 1 and viewed inthe direction of the arrows;

Fig. 3 is an enlarged fragmentary view of the armature support employedin Figs. 1 and 2 taken along the line 3-3 of Fig. 4 and looking in thedirection of the arrows;

Fig. 4 is an enlarged section taken along the line 4-4 of Fig. 1 andviewed in the direction of the arrows;

Fig. 5 is a view, similar to that of Fig. 4, of a modification of thearmature support employed in the ringer illustrated in Figs. 1 and 2;and

Fig. 6 is a section taken along the line 6-6 of Fig. 4 looking in thedirection of the arrows.

In the drawing, in which like numerals in the several figures identifysimilar parts, I is a U- shaped permanent magnet whose two spaced endsare joined by a cross-bar 2 of magnetic material and secured thereto,preferably by welding. Integrally associated with the cross-bar 2 is asubstantially V-shaped bracket 5 having two di-- verging arms 6 and l tothe ends of which are secured gongs 8 and 9 respectively, by means ofscrews Ill. Each gong is cushioned to its respectivasiipport by meansofa grommet or eyeletshaped rubber bushing II which encircles the shank ofscrew l and is interposed between the bracket finger and screwhead. Thiselement serves to insulate the gong from the mounting and causes thesound output to be predominately the pleasing quality air-born sound ofthe gong instead of containing those unpleasant noise componentsincidental to the mechanicalsystem and transmitted through the mounting.The striker-rod i3 is staked or otherwise rigidly secured to thearmature 26.

The magnet cores 3 and 4 have their upper ends abutting the cross-bar 2and are each provided with an axial tapped bore which accommodates ascrew IS. The screws l pass through apertures in the cross-bar 2 and arethreaded into the cores 3 and l.

A plate ll of comparatively stiffinsulating material, such as phenolfibre, serves as a common upper spoolhead for the coils 22 and isprovided with apertures through which the upper ends of cores 3 and 4extend. Along the outer edge of plate l4 there is provided a series ofnotches 2| which accommodate the upper end of a biasing spring 55 whoselower end is staked into the armature. By shifting the spring end fromnotch to notch, the biasing of the armature may be varied.

The windings 22 of the electromagnets are wound on the cores 8 and 4between the plate i4 and the circular spoolheads 23 located on the lowerends of the cores.

The lower end of each of the cores3 and 4 has an enlarged portion 24projecting below the spoolheads 23. The portions 24 are knurled with astraight knurl so that sharp, vertical spaced ribs are formed on thecore ends. A yoke 31 formed of two integrally joined annular portions isforce-titted to the enlarged core ends 24 with the apertures in theannular portions accommodating the core ends. The portion of the yokejoining the two annular portions has two oppositeiy disposed upturnedintegral projections 38 each of which is split downwardly as indicatedat 40.

The armature 26 which extends over the enlarged core ends 24 is providedwith a pair of oppositely disposed integral projections 28, one of whichis split at 29 in a manner similar to the projections 38 of the yokepiece.

,A shaft or rod 4|, as shown in Fig. 4, has one end staked to theunsplit armature projection 28 and the portion thereof extending to theleft of the staked portion, as viewed in Fig. 4, is encased in acylindrical sleeve 46 of rubber, the rubber .being vulcanized orotherwise secured to the shaft.

Prior to the staking of the shaft 4| to the armature, the portions ofthe armature projections formed by'the split 29 and the portions of theyoke projections effected by the splits 40 are separated or distended toallow the rubber encased shaft to be set in position and the separatedportions are then squeezed together. The rubber sleeve is accordinglypinched by yoke extensions 38 as well as by the slit armature extension28. The shaft is then staked to the armature as indicated at 44. Thisarrangement provides a rigid association of the shaft with the armatureand a torsional coupling between the armature and stationary yoke. Anyother method of securing the sleeve to the, yoke such as by cementingwould serve equally as well. The squeezing of the sleeve by the slittedarmature projection is preferred only for mechanical reasons, therebeing no advantage so far as this invention is concerned'in havingresilient means in ,Fig. 4 betwen the armature and the shaft.

when the ringer is energized, the armature is attracted alternately tothe two poles of the electromagnets and due to the fact that thearmature is staked or otherwise rigidly secured to the rod 4|, thelatter rotates back and forth with the armature and tends to carry thesleeve 46 with it. Since the yoke and that part of the sleeveimmediately adjacent thereto are stationary, it is obvious that therubber directly between the shaft and the yoke undergoes a torsionaldeformation.

The shaft is preferably of such size as to make a rugged support and thecomposition and dimensions of the rubber sleeve can be such as to allowany'desired freedom of torsional motion to the armature. The impedancethat the rubber offers to such motion is not variable with time nor doesit depend upon lubrication or the environment with respect to dirt.

Each pole face of the armature 26 is provided with a rubber stop to actas a cushion between the armature and core pole-pieces 24 and therebyreduces noise caused by the operation of the armature to a minimum. Theheads of the stops 45 are preferably of different thicknesses forwellknown reasons and either may be changed to regulate the volume ofsound as desired.

In the modification shown in Fig. 5, the shaft 4| is shown staked to theyoke 31 and with a bushing 48 vulcanized or otherwise cemented to eachend portion. The bushings 48 may be squeezed or pinched by the extension28 of the armature 26. The objective is to obtain a rigid connectionbetween the shaft and yoke and a torsional coupling of the yoke andarmature.

The rod 4| and its elastic sleeve may be considered to constitute acompound shaft whose elastic fatigue is considerably lower than that ofmetal and which, therefore, will have a longer life of service than ametal reed used for the same purpose.

The principle of operation of the particular type of ringer selected toillustrate the invention is the same as that of the ringer disclosed inPatent 2,082,095 issued to H. A. Bredehoft. In such structures thepermanent magnet I is so magnetized that the mid-point of the piecejoining the two parallel arms will repel the north seeking pole of acompass needle so that the two ends of the armature 26 have the samepolarity, that is they present like poles to the lower extremities ofthe cores 3 and 4. The windings 22 of the electromagnets are connectedin series so that current traversing one winding will be in a downwarddirection when the current in the other winding is in an upwarddirection with the result that the lower ends of cores Sand 4 presentunlike poles to the armature ends. For example, when the lower end ofcore 3 is north due to the current traversing the right winding 22, thelower end of core 4 is south due to the current traversing the leftwinding 22 and these polarities reverse for each half cycle of theringing current. Thus, when there is a force of attraction between thepole end of core 3 and the armature end oppositely disposed thereto,there will be a force of repulsion between the pole and of core 4 andthe armature end oppositely disposed thereto. In this manner thearmature 26 oscillates about its support when the windings 22 areenergized from a source of signaling current.

What is claimed is:

1. In an electromagnetically operated telephone ringer, a stationaryyoke, a movable armature and a compound torsional coupling between saidyoke and said armature having an elastic fatigue less than metal andcomprising a rubber sleeved shaft, the sleeve thereof being fixedlyassociated with both said armature and said yoke and vulcanized to saidshaft.

2. In an electromagnetically operated telephone ringer, a stationaryyoke, a rotatable armature and means for mounting said armature on saidyoke comprising a shaft, and a rubber sleeve vulcanized to said shaft,said shaft being mechanically staked at one end to said armature forrotation therewith and said sleeve fixedly associated with both saidarmature and said yoke.

3. 'In an electromagnetically operated telephone ringer, a stationaryyoke having a pair of split integral projections extending at rightangles to the main body portion thereof, a movable armature having apair of split integral projections extending therefrom, the splitprojections of said yoke and armature being in alignment, and means formounting said armature on said yoke comprising a rubber sleeved shaft,the sleeve of which is vulcanized to the shaft and clamped between thesplit portions of the armature and yoke pro- 10 iections.

4. In an electromaghetically operated telephone ringer, a stationaryyoke, an armature rotatable relative to said yoke and a rubber sleevedrod interconnecting said yoke and said armature, the sleeve thereofbeing fixed against rotation relative to said yoke and said armature andvulcanized to said rod and said rod being rotatable with said rotatablearmature. I A

DAVID G. BLATTNER.

